“In July 2010, a U.S. spy agency intercepted electronic communications indicating that senior al-Qaeda leaders had distributed a ‘strategy guide’ to operatives around the world advising them how “to anticipate and defeat” unmanned aircraft,” the Post reported. “The Defense Intelligence Agency (DIA) reported that al-Qaeda was sponsoring simultaneous research projects to develop jammers to interfere with GPS signals and infrared tags that drone operators rely on to pinpoint missile targets.”

Other projects include surveillance of drone flight patterns through observation balloons and radio-controlled hobby aircraft.

A 2010 CIA report noted that al-Qaeda leaders, many of whom have an engineering background, were emphasizing “the recruitment of technicians and that ‘the skills most in demand’ included expertise in drones and missile technology,” said the Post.

The Defense Intelligence Agency (DIA) has also uncovered evidence of attempts to develop GPS jamming, while the U.S. Army discovered that militants were researching laser detectors to warn of drone-launched missiles. In 2009, Iraqi insurgents were found to have successfully intercepted unencrypted video imagery from U.S. drones.

While al-Qaeda’s anti-drone techniques have apparently been unsuccessful, the Pentagon is worried that U.S. drones are vulnerable, especially in their command links. “Summaries of the classified reports indicate a growing unease among U.S. agencies about al-Qaeda’s determination to find a way to neutralize drones,” the Post said.